Introduction

The cloud forests of northeastern Peru are part of the Tropical Andes biodiversity hotspot, and home to three endemic Peruvian primates: the Andean night monkey (Aotus miconax), the Andean titi monkey (Callicebus oenanthe), and the Peruvian yellow-tailed woolly monkey (Oreonax flavicauda) (see Aquino and Encarnación 1994; Pacheco 2002; Rylands et al. 1995). The Andean night monkey is known only from collections by E. Heller in the region of Huánuco (Aquino and Encarnación 1994), and R. W. Hendee in the region of San Martín (Thomas 1927). It is believed to occur in a very restricted area, west and south of the Río Huallaga, to about 10°S on the eastern slope of the Andean highlands, in the departments of Amazonas, San Martín, La Libertad and Huánuco (Ford 1994; Hershkovitz 1983). It is sympatric with the two other endemic Peruvian primates. Aotus miconax belongs to the “red neck group” of night monkeys. (Hershkovitz 1983), presenting many similarities with A. nancymaae but, due to the lack of available information, no conclusive taxonomic arrangements could be provided by Hershkovitz (1983) or Ford (1994). It is categorized as Vulnerable on the IUCN Red List of Threatened Species (IUCN 2008), and as “Endangered” by Peruvian Law (Decreto Supremo 34-2004-AG; see Heymann 2004).

Besides museum specimens and field sightings by Butchart et al. (1995), nothing is known of its biology and natural history. In this note we are presenting some observations on the natural history of the species, as well as some remarks on the distribution and conservation status of this primate endemic to Peru.

Natural History Observations

Site 1. Abra Patricia—Alto Nieva

We occasionally saw A. miconax during the course of a study on the ecology and behavior of the yellow-tailed woolly monkey, O. flavicauda, in the Private Reserve Abra Patricia-Alto Nieva in the department of Amazonas (Cornejo in prep.). This reserve of 2,065 ha has primary and secondary cloud forest, with some small human settlements around it. We saw them 11 times in all, between the months of March and June 2007; the contact time ranged from seven to 33 minutes. A. miconax was observed in both primary cloud forest and in disturbed forest fragments very close to human settlements, between 1,980 and 2,348 m above sea level. Group size ranged from two to four, with an infant observed once (Table 1). Two sleeping sites were identified. We observed one group when entering a sleeping site at 06:05, and another group when leaving it at 18:15. One of the trees was of the genus Ficus (Moraceae) and the other Ocotea (Lauraceae). Both were heavily covered by epiphytes, climbers and vines, with the sleeping sites located at heights of 7 m and 9 m, respectively, among branches, epiphytes and vine tangles. Individuals were also observed eating fruits from the genus Ficus and flowers from an undetermined tree of the Melastomataceae family.

Table 1.

Sightings of Aotus miconax.

During one sighting, we saw two individuals moving approximately 10 m from a group of resting O. flavicauda, with no sign of reaction from either group regarding the presence of the other species. Another sighting was during daylight at 15:18. The night monkeys were moving through the tree branches until they settled in a Cecropia tree. After noticing our presence, they quickly fled. There was no apparent human disturbance prior to the encounter that may have caused the group to be out of its sleeping site.

Distribution of Aotus miconax in the Departments of Amazonas and San Martín

Aotus miconax was described by Oldfield Thomas (Thomas, 1927a) from specimens collected by R.W. Hendee in the area of San Nicolas (in a valley called Huayabamba) in Peru's Department of Amazonas. Soon after this first collection, R. W. Hendee provided another specimen from Tingo María, in the Department of Huánuco (Thomas, 1927b). Other records of A. miconax were identified by Hershkovitz (1983) in his revision of the genus. He attributed specimens collected by E. Heller in 1922 along the Río Chinchao and from Tingo María, Huánuco (Field Museum of Natural History, Chicago) to A. miconax. Aotus miconax is also known from sightings in Comboca and San Cristóbal in Amazonas by Butchart et al. (1995). Mittermeier et al. (1975) and Leo Luna (1984) reported the presence of night monkeys (referred to then as A. trivirgatus) in the cloud forests of Pedro Ruiz Gallo and Venceremos, and these are probably referable to A. miconax. Tingo Maria is also the locality of some A. nigriceps collections, so whether these two species are sympatric in this area remains unknown.

Table 2.

Records of Aotus miconax.

Figure 1.

Localities where A. miconax has been recorded.

Further information on the occurrence of this species (sightings and interviews with local people) was collected during the course of faunal evaluations in the departments of San Martín and Amazonas between August and November of 2005. The surveys included a range of habitats between 900 and 2,600 m above sea level (Table 1). In San Martín, the presence of night monkeys was confirmed in the areas of Los Chilchos and Mashuyacu to the west, very close to the boundary with the department of Amazonas; and in the south, in the Río Tocache basin, from the Río Grueso to near the boundary with the department of La Libertad. In Amazonas, the species has been recorded in the eastern forests at the border with San Martín, from the headwaters of Los Chilchos and the Río Verde in the south, to the basin of the Río Nieva in the north, above 1,300 m above sea level. In the central area, the species occurs in the forests on the left bank of the Río Utcubamba, from Choccta to the headwaters of the Río Imaza in the north (Fig. 1).

Aotus miconax was seen to use a variety of habitats at all sites: primary and secondary montane forests on steep and very steep slopes; the ecotone with timberline forests, and relict forests.

Conservation Status

Locally known as “tutacho” or “mono de noche”, Aotus miconax occurs in the governmental protected areas Parque Nacional Río Abiseo (274,520 ha, Aquino and Encarnación 1994) and possibly in the Zona Reservada Cordillera de Colán (64,115 ha, Butchart et al. 1995). Here the species has now been recorded in Bosque de Protección Alto Mayo (182,000 ha, local informants, near the town of Alto Nieva), the private reserves Abra Patricia—Alto Nieva (2,065 ha) and Huiquilla (1,000 ha), and in the Municipal Reserve Cuenca del Río Huamanpata (23,097 ha).

Being small and having pungent subcaudal scent glands, night monkeys are not hunted for food (Aquino and Encarnación 1994). Nonetheless, a skin was collected from a hunter living in the surroundings of the Abra Patricia—Alto Nieva reserve, and we have recorded at least four families with pets of A. miconax in the last two years. Butchart et al. (1995) also reported a pet in a village near the Zona Reservada Cordillera de Colán. Local people claim they do not hunt A. miconax, neither for the pet trade or food, nor because they eat their crops (as do Cebus albifrons and O. flavicauda). Individuals are caught, however, when their sleeping trees are cut down when clearing the forest for pasture or crops. They are usually then kept as pets, but tend to die within a few weeks.

Most of the primary cloud forest in the range of A. miconax has been destroyed and replaced by croplands and pastures. These forests were virtually inaccessible until the 70s, when highway construction was begun, traversing the departments of Amazonas and San Martín (Leo Luna 1984). This highway allows the immigration of thousands of people with agriculture and livestock practices incompatible with the characteristics of cloud forest soils. As a result, Amazonas and San Martín have the highest rates of deforestation and immigration in Peru (Elgegren 2005; Peru, INEI 2006). Although A. miconax is common where it occurs, and can persist in disturbed, secondary and relict forests, some areas of its supposed historical distribution are so deeply disturbed that the species has become locally extinct. The extremely high rates of deforestation pose a very real threat of the irreversible loss of this ecosystem, where not even officially protected areas provide guarantee for appropriate conservation of these forests. Urgent conservation measures are needed to protect these forests and the species they harbor. Further research on the habitats, range, habits and status of A. miconax is needed.